1. Field of the Invention
The present invention relates to a sunshade apparatus for an automobile which includes a sunshade screen adapted to be unwound and extended from a take-up roll to intercept sunlight transmitted through a rear window of an automobile.
2. Description of the Prior Art
In general, a sunshade apparatus for an automobile is designed to be driven by an electric motor such that a sunshade screen can be conveniently manipulated by a driver seated in a driver""s seat to be extended from and wound around a take-up roll.
An electric sunshade apparatus is disclosed in EP Patent No. 601,454, which comprises a stationary rod which is provided at its middle point with an upright rail having a rack, a movable frame which is provided at its middle point with a slider engaged to the rail and having a pinion engaged with the rack of the rail such that the movable frame is slidable up and down relative to the stationary rod, a sunshade screen coupled at its both ends to the stationary rod and the movable frame and wound around the movable frame, and a driving motor connected to the movable frame to rotate the pinion.
In other words, such an electric sunshade apparatus is designed to spread or wind the sunshade screen by the pinion of the movable frame, which is engaged with the rack of the stationary rod and is rotated and thus moved up and down along the rail by the driving motor. Therefore, since a rear window of an automobile is always occupied by the rail having the rack, a rear window becomes unsightly and forms an obstacle to the field of view of a driver.
In addition, since the movable frame having considerable weight due to the pinion, the slider, the driving motor, a gearbox and the wound screen must be raised so as to spread the sunshade screen, the driving motor is applied with high load and considerable electrical energy is required to operate the sunshade apparatus. Furthermore, since the driving motor and the gearbox are positioned inside an automobile, operational noise thereof is directly transmitted inside of an automobile.
To overcome the problems occurring in the above electric sunshade apparatus disclosed in EP Patent No. 601,454, Korean Utility Model Registration No. 0182090 allowed to the inventor has been proposed.
The sunshade apparatus disclosed in Korean Utility Model No. 0182090 is adapted to spread or wind a sunshade screen by raising or lowering a movable rod to which the screen wound around a stationary roll is coupled. More specifically, first and second actuating bars are pivotably connected at upper ends thereof to opposite ends of the movable rod. The first and second actuating bars are also pivotably connected to first and second sliders, which are disposed on a frame to be slid laterally. A pair of idle pulleys are positioned at both sides of the frame. A cable is wrapped over the pair of pulleys, and fixed at its both ends to a driving pulley mounted on the frame with the both ends of the rope being slightly wound around the driving pulley. One of the first and second sliders is fixed to an upper rope section and positioned at one side of the driving pulley, and the other of the sliders is fixed to a lower rope section and positioned at the other side of the driving pulley.
In the sunshade apparatus, when the driving pulley is rotated clockwise or counterclockwise by a driving motor, the first and second sliders are moved toward or away from each other, thereby causing the first and second actuating bars to be inclined or to be erected. Hence, the movable rod is lowered or raised by the tilting movement of the first and second actuating bars, so that the sunshade screen fixed to the movable rod is elastically wound around the stationary roll or extended upwardly.
Although the said sunshade apparatus of the inventor can substantially overcome the problems occurring in the electric sunshade apparatus of EP Patent No. 601,454, since the driving means is mounted on the frame and positioned inside of an automobile, it is impossible to fundamentally overcome a problem caused by the operational noise.
Furthermore, since the power transmission means is comprised of a single wire cable, it is very difficult to provide sufficient tension to the wire cable wrapped over the pulleys, and it is impossible to preserve a precise operation of the device due to relaxation of the wire rope upon use for a long time.
In addition, since extension of retraction of the sunshade screen is fulfilled by only turning force of the driving motor, delayed actuation and overload are caused in an initial operation. Moreover, since assembled components are loosened by vibrations generated during starting and stopping of an operation, operational reliability is lowered.
Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a sunshade apparatus for an automobile which is provided with driving means such as a driving motor and a gear box generating operational noise, which are installed to be isolated from a frame positioned in an interior of an automobile.
Another object of the present invention is to provide a sunshade screen for an automobile which is provided with power transmission means comprised of several cables having different moving ranges to facilitate tight assembly of the cables.
A further object of the present invention is to provide a sunshade apparatus for an automobile which is improved in operational reliability and durability by increasing initial driving force or reducing vibrations.
In order to accomplish the above object, the present invention provides a sunshade apparatus comprising: a take-up shaft biased by an elastic element to be rotated in a winding direction; a sunshade screen coupled at its one side to the take-up shaft and wound therearound; a shade bar to which the other side of the sunshade screen is coupled; a frame having first and second sliders slidably engaged therewith; first and second actuating bars pivotably coupled at both ends thereof to the shade bar and the first and second sliders; a drive assembly including a driving motor adapted to be rotated in forward and reverse directions, a worm wheel rotated by the driving motor, and a rope drum engaged with the worm wheel and having a helical groove; first and second transmission cables connecting the rope drum and the first and the second sliders and wound around the rope drum, and a mediate cable connecting the first slider and the second slider; and first and second shock absorbers associated with the first and second sliders.